using System.Text.Json;

namespace Campaign_Tracker.Server.LegacyData.Schema;

public sealed class FileLegacySchemaCheckHistory : ILegacySchemaCheckHistory
{
    private readonly string _filePath;
    private readonly object _fileLock = new();

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
    };

    public FileLegacySchemaCheckHistory(string filePath)
    {
        if (string.IsNullOrWhiteSpace(filePath))
        {
            throw new ArgumentException("History file path is required.", nameof(filePath));
        }

        _filePath = filePath;
        Directory.CreateDirectory(Path.GetDirectoryName(_filePath) ?? ".");
    }

    public void Record(LegacySchemaCheckResult result)
    {
        ArgumentNullException.ThrowIfNull(result);
        var line = JsonSerializer.Serialize(result, JsonOptions) + Environment.NewLine;
        lock (_fileLock)
        {
            File.AppendAllText(_filePath, line);
        }
    }

    public IReadOnlyList<LegacySchemaCheckResult> GetRecent(int maxCount = 50)
    {
        if (maxCount <= 0 || !File.Exists(_filePath))
        {
            return [];
        }

        lock (_fileLock)
        {
            return File.ReadLines(_filePath)
                .Where(line => !string.IsNullOrWhiteSpace(line))
                .Select(line => JsonSerializer.Deserialize<LegacySchemaCheckResult>(line, JsonOptions))
                .Where(result => result is not null)
                .Cast<LegacySchemaCheckResult>()
                .OrderByDescending(result => result.CheckedAt)
                .Take(maxCount)
                .ToArray();
        }
    }
}